PIs: Martin Deschnes, Yoav Freund, David Golomb, David Kleinfeld (lead), Fan Wang ! Core 2. Abstract Precision Histology This Core provides high-throughput tape transfer sectioning to cut near perfect stacks of slices of the whole brain, from olfactory bulb to spinal level C2. The tape transfer histology system has been in continuous operation in the Mitra laboratory for several years and will enable the registration of anatomical data from Research Projects 1, 2, and 3, into a common framework established by the Trainable Texture-based Digital Atlas. Control of orofacial actions is coordinated by distinct populations of brain stem premotor neurons that are arranged into relatively small clusters and limited to domains as small as 200 to 300 m in extent. For many orofacial motor actions, premotor neuronal clusters are present at multiple levels of the brainstem and do not conform to the boundaries previously defined by available atlases, including the Paxinos atlases and the Allen Brain Common Coordinate Framework atlas. As part of our concerted effort to identify the functional organization of brainstem motor control, we require standardized processing of brain tissue. The established histology pipeline in the Mitra laboratory offers key advantages over alternative methods, in that tissue is retained in near perfect alignment during sectioning and is amenable to standard histological stains that demarcate brainstem landmarks used to align and annotate brains. Crucially, this approach precludes distortions from classical sectioning methods and enables efficient 3D reconstructions, cross-brain registration, and efficient incorporation of data from new brains into our recently developed Trainable Texture-based Digital Atlas. By efficiently multiplexing labeled neurons from transsynaptic tracing, in vivo recordings, and transgenic mice/cell type marker stains, the Precision Histology Core serves to support data compilation into a common anatomical framework.